Adherence to antiretroviral therapy (ART) is a serious challenge for many people living with HIV (PLWH). Inconsistent adherence is associated with poor clinical outcomes, treatment failure, and increased healthcare costs. Pharmacists are uniquely positioned to promote adherence to ART given their proximity to PLWH and training, yet they remain an underutilized resource in the management of HIV infection. Pilot studies indicate that pharmacist-implemented adherence promotion activities (e.g., medication-specific education, follow-ups to monitor adherence), can be highly effective in increasing adherence to ART and improving patient health outcomes. Our preliminary qualitative study indicated that many pharmacists already use multiple strategies to prevent and resolve adherence barriers that disrupt therapy, but pharmacists face challenges that interfere with their ability to promote ART adherence. For example, insurance companies have instituted structural-level cost containment strategies (e.g., use of mail-order pharmacies) and micro-level cost containment policies (e.g., prior authorization requirements) to control prescription drug expenditures. These cost containment policies-- which influence PLWH's access to adherence promotion activities--remain understudied. The proposed R21 will use a cross-sectional quantitative survey to: 1) examine and compare adherence promotion activities in community-based specialty and traditional pharmacies, and mail-order pharmacies; 2) identify facilitators and barriers to providing these services; and 3) analyze the role of structural-level insurance cost-containment policies that mediate and moderate pharmacist-implemented adherence promotion activities in different real world pharmacy settings. We will recruit pharmacists from 75 specialty and 75 traditional pharmacies located in 10 high HIV prevalence MSAs, and 75 mail-order pharmacies from a nationwide sample, to complete an online survey. We will develop a survey questionnaire using our preliminary qualitative study and published literature about adherence promotion activities, barriers and facilitators to promoting these activities. The proposed R21 study is significant in that, to our knowledge, it will be the first to examine and compare ART adherence promotion activities in different real world pharmacy settings, and to analyze the impact of specific cost containment policies on pharmacists' adherence promotion activities that impact PLWH's access to high quality pharmacy care. The proposed R21 study will provide the framework for a future R01 cost-effectiveness study; and an economic evaluation of the impact of pharmacy adherence promotion activities on PLWH's health outcomes, and healthcare use and costs in different pharmacy settings.